San Francisco Sheriff Ross Mirkarimi announces to reporters he refuses to resign his post following an ultimatum by Mayor Ed Lee, March 20, 2012. (CBS)

SAN FRANCISCO (CBS SF) — Suspended San Francisco Sheriff Ross Mirkarimi acknowledged a violent act against his wife but denied attempts at a cover-up during the start of his testimony Thursday night at the administrative hearing to determine whether he can keep his job.

Mirkarimi was suspended by Mayor Ed Lee in March on official misconduct charges following his guilty plea to misdemeanor false imprisonment in connection with a Dec. 31 argument with his wife, Eliana Lopez, in which he grabbed and bruised her arm.

He appeared Thursday night before the city’s Ethics Commission to defend himself against the charges, giving mostly terse answers under questioning by Deputy City Attorney Peter Keith on the duties and policies of the sheriff, as well as the events of New Year’s Eve and the following days.

“Sheriff, you committed an act of violence on Dec. 31, correct?” Keith asked.

Mirkarimi gave a string of “Yes” answers to questions asked by Keith, including one in which he was asked if his conduct reflected adversely on the sheriff’s department.

Mayor Lee, via the city attorney’s office, has argued that Mirkarimi’s conviction, for which he was sentenced to three years’ probation and other penalties, prevents him from adequately serving the duties of sheriff and falls below the standard of decency expected of an elected official.

The city attorney’s office has also alleged that Mirkarimi used his power as a public official against Lopez and to dissuade witnesses in the days following the Dec. 31 incident, but Mirkarimi denied that, saying he was busy with the transition from serving as supervisor to being sworn in as sheriff on Jan. 8.

“It was chaotic, there was a lot of moving going on,” he said.

Mirkarimi’s testimony will resume on Friday morning and is expected to be followed by the mayor, who Ethics Commission chair Benedict Hur estimated would begin testifying by late morning.

Under the city charter, the commission is tasked with holding hearings on the administrative charges and collecting evidence and will eventually make a recommendation to the Board of Supervisors on whether to remove Mirkarimi from office or reinstate him as sheriff.

Before Mirkarimi’s testimony Thursday night—which lasted a little under an hour—the commission addressed other issues including the admissibility in the proceedings of a video of Lopez recorded by a neighbor, Ivory Madison, who later reported the incident to police.

The commission agreed that the video should be admitted, and also discussed the potential live testimony of Lopez, who has since gone to her native Venezuela to care for her ill father.

Lopez’s attorney, Paula Canny, told the commission that Lopez is willing to provide live testimony in mid-July if the city pays for a roundtrip flight to the U.S.

Hur brought up the possibility of Lopez testifying by a Skype live video feed, but Canny said live testimony would be preferable to better show “my client is credible and telling the truth.”

Lopez submitted a written declaration earlier this week defending Mirkarimi and denying any attempts at a cover-up by him.

The decision on Lopez’s testimony was tabled until the city attorney’s office could talk to the mayor Friday about whether payment for a flight for her could be arranged.

The commission will return to resume the hearing at 9 a.m. Friday at City Hall, with more hearings planned in July.

Once the case goes to the Board of Supervisors, nine of the 11 supervisors would have to approve of ousting Mirkarimi from office.

Mirkarimi served as a supervisor for seven years before being elected sheriff in November and taking office in January.

(Copyright 2012 by CBS San Francisco and Bay City News Service. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.)